The present invention relates to a sealing member, a rolling bearing, a thin motor and a bearing device. The sealing member is used to close the end part opening of a space part having rolling elements of a rolling bearing. In addition, the rolling bearing is used for providing a rotation supporting part for various kinds of machinery. Further, the thin motor is used, for example, as a motor for rotation drive of various kinds of devices, such as a disc driving motor constituting a magnetic disc drive device including a hard disc drive device (HDD), and a floppy disc drive device (FDD), a cooling fan driving motor for an IC, and a polygon mirror driving motor for a laser beam printer (LBP).
The present invention also relates to a rolling bearing or a bearing device, specifically, it relates to that preferable as a small bearing or bearing device to be used for a spindle motor, a swing arm, a motor for an IC cooling fan, or the like, in information appliances such as a hard disc driving device, a floppy disc driving device, and an optical disc driving device.
For example, a hard disc is rotated by a direct drive type spindle motor at a high speed at the time of using an HDD as a memory device for a computer, or the like. A space part provided with a rolling element, of a rolling bearing constituting a rotation supporting part of such a spindle motor has a lubricating grease sealed therein so as to lubricate the rolling contact part between a plurality of rolling elements, and inner and outer ring raceway tracks. Furthermore, both end opening parts of the space provided with the plurality of the rolling elements are closed by a sealing member such as a sealing plate, and a shielding plate. Thereby, leakage of the grease from the space part provided with the rolling elements to the outside can be prevented as well as entrance of a foreign substance such as dusts and moisture into the space can be prevented.
In order to save the space inside a casing storing an HDD, or the like, a thin motor with a smaller axial direction size is used as the above-mentioned spindle motor. In the case of producing such a thin motor, the axial direction size of a rolling element to be assembled as a rotation supporting part of the thin motor needs to be made smaller. In order to have the axial direction size of the rolling bearing smaller, the axial direction size of an outer ring and an inner ring constituting the rolling bearing needs to be made smaller. In contrast, the diameter or the axial direction size of the plurality of the rolling elements cannot be made drastically smaller for ensuring the bearing load of the rolling bearing. Therefore, if the axial direction size of the rolling bearing is made smaller in consideration of the circumstances, the axial direction distance between the axial direction end surface of each of outer and inner rings and the rolling contact surface or the axial direction distance between the axial direction end surface of each of outer and inner rings and the axial direction end rim is made shorter. As a result, installation of an engaging groove, or the like for engaging the sealing member on the end part inner circumferential surface of the outer ring or the end part outer circumferential surface of the inner ring can be difficult, or even in the case the engaging groove can be provided, engagement of the sealing member with the engaging groove can be difficult due to interference by the rolling elements.
In addition, conventionally, as a bearing for a hard disc driving device, that having two ball bearings disposed via a spacer can be presented. Moreover, according to downsizing of a motor for the hard disc driving device, there is a demand for an extremely small bearing width (axial direction size) of, for example, 2 mm or less. In a bearing with such a small width, it is difficult to provide a seal in the bearing. In other words, if a seal is provided in a bearing, it is difficult to have an extremely small bearing width of, for example, 2 mm or less.
In the case a seal is not provided in a bearing, a problem is involved in that dusts can easily enter into the bearing at the time of assembling the bearing with a shaft and a housing, or at the time of mounting a bearing device with the bearing disposed between an axis side member and a housing onto a chassis. However, conventionally, a countermeasure has not been provided sufficiently therefor.